Sometimes you will miss some OOTB workflows in your vCenter Orchestrator library. The last time I searched for a workflow the customer task was:
"Add a second disk with a different controller type and and a new bus ID (1)."
Reading this the task sounds really simple, but when searching there is only an "Add disk" workflow in the library which always crashes if you set the bus ID to 1, cause there isn´t a second SCSI controller.
Also there is no workflow to add a second SCSI controller and there is no method in the vSphere Client. So I decide to check how the vSphere client handle this event and used Onyx (http://labs.vmware.com/flings/onyx) to look for the used specifications.
So I found out that there is only an "add disk" method in the vSphere Client which automatically adds a second SCSI controller. With this knowledge I build a workflow which adds a second SCSI controller and then a second hard disk on this SCSI controller.
First make a clone of the "createVirtualScsiControllerConfigSpec" action and change the lines:
controller.key = 1;
controller.busNumber = 1;
Now create a new workflow and add a "Scriptable Task" element and the "vim3WaitTaskEnd" action. My IN parameter are: the VM (VC:VirtualMachine), the diskSize (number), the datastore (VC:Datastore) and the thinProvisioned (boolean) switch. The attributes are: task, progress, pollRate.